Chapter XV. Differential Diagnosis

Description

This section is from the book "Skin Cancer", by Henry H. Hazen, A.B., M.D.. Also available from Amazon: Skin Cancer.

Chapter XV. Differential Diagnosis

In dealing with cutaneous neoplasms, there are two essentials- first, to decide whether the new growth is an inflammatory one or a true neoplasm, and, second, to decide whether, if it be a true tumor, if it be malignant or benign. If it be malignant, it is necessary to further decide whether it be a prickle-celled tumor, or a basal-celled growth, or if it be a sarcoma.

In order to decide this question accurately, it is often necessary to approach the problem in three different ways-first, the clinical aspects of the new growth; second, its gross pathology as seen by the naked eye; and third, its histological structure as seen by the microscope. The better the pathologist that the operator is the more frequently will he be able to make a diagnosis from the first two of these criteria, and hence the more promptly will the patient be dealt with and the necessity for second operations lessened.

History

The first point is to obtain a careful history from the patient. The age must always be noted. It is rare for malignant epithelial tumors to arise before the age of thirty, except in the condition known as xeroderma pigmentosum. Nor does a mole often become malignant under the age of forty. Likewise / sarcomata of the skin are not common in the young.

The occupation of the patient must always be noted, for malignant tumors of the basal-celled variety not infrequently develop in those who have been much exposed to actinic rays, whether produced by the sun or by the rontgen tube. Those who are engaged in the manufacture of paraffin and tar are especially liable to cutaneous cancer.

Furthermore, it should be decided whether there was a precancerous dermatosis antedating the new growth. From the common senile warts we usually find a basal-celled carcinomata resulting; from an x-ray burn a prickle-celled neoplasm is much more likely to arise. If the growth be from a pigmented mole, we are usually dealing with either a nevocarcinoma or multiple melanomata, both very malignant. In the scars of old wounds prickle-celled growths or sarcomata may arise, while from vascular nevi we practically find only sarcomata.

The duration of symptoms is likewise of special import, for the more malignant the tumor the more rapidly it grows. A basal-celled tumor may grow more rapidly than a prickle-celled one, but this is rare.

With a deeply seated neoplasm it is always best to exclude syphilis, and, to decide on this point, the patient's word should never be accepted, but the diagnosis confirmed by the various laboratory tests, remembering that both the Wassermann and luetin reactions may be negative in long standing cases of this malady, and hence not putting too much reliance in them. At times a superficial gumma before ulceration may almost exactly resemble a nodular or rolled-edge rodent ulcer.

The symptoms of onset must be noted, and what was the first, pain, itching, serous discharge denoting superficial ulceration, or the presence of a nodule. It must always be remembered that pain is comparatively rare in skin tumors, whether malignant or benign.

The later symptoms must be carefully asked for in order to determine as to the possibility of metastases. While cachexia is extremely rare in skin cancers, yet metastases from them may cause these symptoms. In large ulcerating growths the absorption of toxins from secondary bacterial infection may cause a picture of cachexia.

The local signs and symptoms are much more important than the general; we must always try to find out how rapidly the tumor grew when first observed, and how rapidly it has grown within the past few weeks.

Examination

In the examination of the growth, certain facts must be observed. First, we should note the r^latKHTof the tumor to the skin, for certain tumors arising from the Tappendages may not at first be adherent to the epidermis, while the basal- and prickle-celled growths almost invariably are attached to the skin from the incipiency. On inspection we must note the size of the growth- whether it is exuberant or whether it has formed a deep ulcer. The character of the surface must be observed, for prickle-celled neoplasms usually have a very rough and irregular surface. The amount and character of the discharge is important, for absorption may cause many general symptoms. Metastatic growth, either in the vicinity or in the glands, must be looked for. And especially important is the situation of the tumor, for growths on the face except the lips are usually comparatively benign, while those upon the extremities are usually very malignant. Likewise, if there be multiple growths, they are probably of a basal-celled origin, if not examples of multiple sarcomata.

On palpation the character of the induration is especially important, for the carcinomata invariably have an extremely hard edge, while in inflammatory lesions this is lacking as a general rule. The depth of the induration is likewise important, for in the malignant growths this is usually considerable. It must always be borne in mind that there may be an inflammatory induration that may simulate a cancerous one. The neighboring glands should always be palpated, again remembering that an enlargement of them can denote an inflammatory condition.

Gross Pathology

After a tumor is excised, it should be sectioned at once in order to determine its variety and the depth of its infiltration. In the squamous-celled cancers the infiltration is comparatively deep and wide. These growths also show a characteristic picture on section, for there can be observed fine white lines, about the size of fine sewing cotton, radiating downward from them, a condition totally lacking in the inflammatory conditions, and usually not marked in the basal-celled growths, where the cancerous alveoli are smaller.

In obtaining material for microscopic study, certain precautions must always be observed. Among the majority of surgeons there is a strong feeling that it is frequently dangerous to excise a portion of a tumor for examination if that tumor be of a malignant nature, for incision leaves a number of gaping blood vessels and lymphatics into which cancer cells might escape and thus cause metastases. At the same time, it is occasionally essential to examine such tissue, so the following scheme is usually adopted. If the tumor be upon the lip, or upon a part where it is possible to temporarily constrict the blood vessels by pressure, an assistant does this with his fingers, then a piece is excised under local anesthesia from the edge of the growth, taking care to include a small portion of apparently normal skin, in order to determine the infiltrative powers of the cancer cells, and the wound is then thoroughly cauterized with either the actual cautery or a strong chemical one.

In very early cases it is often impossible to determine from a clinical examination or from the naked eye appearance of the tumor to what variety it belongs, and then the whole growth may be removed and sections made from it.